The present invention relates to energizing an automotive vehicle high voltage bus.
Electric automotive vehicles use high voltage electric traction motors to propel the wheels of the vehicle. The traction motors use a high voltage electrical power source, which is commonly in the form of a high voltage battery. Electrical power is fed to the traction motors from the power source via a high voltage electrical bus.
Typically, two main contactors are used to connect the high voltage electrical bus with the battery, one each in the positive and return leads. Under certain conditions, the high voltage battery is isolated, which is accomplished by opening the contactors. The possibility a main contactor will fail to open when needed increases as the contactors become worn. In order to address this concern, two contactors are used to reduce wear and tear on the contactors and to provide redundancy. Single contactors have been used for circuits where durability is not a concern, but such use is typically limited to low voltage situations, such as a maximum of 120 volts.
However, the use of two contactors in the high voltage bus disconnect circuit increases the complexity and cost of energizing high voltage buses over 150 volts. Known methods of producing high voltage contactors result in individual contactors lasting approximately 200,000 closing and opening cycles. At an average of 3.5 vehicle starts per day, then, a single contactor may last over 150 years.